Proper controls are essential in order to ensure that the results obtained in a scientific experiment were actually caused by the variable being studied and were not a creation stemming from the methods employed. If virologists were to carry out proper controls on their cell culture experiments, they would easily see that the very methods they use are creating the effects they want to observe. Fortunately, there are instances where controls were performed by researchers both in and outside of virology which absolutely show that the exact same “virus” particles can be found in cell cultures without any “virus” material ever being present. From John Franklin Enders invalidating his own cell culture technique in his 1954 measles paper to the numerous examples of researchers finding the same “virus-like” particles in materials from healthy animals in exosome research, the evidence shows that it is the cell culture process, and not the “virus” material, which creates the desired effect.
https://viroliegy.com/2022/07/02/mission-control-the-exosome-escape-clause/: Mission Control: The Exosome Escape Clause